Drive rings are components commonly used in mechanical seals to provide rotational drive between the rotating shaft and the rotary components of a mechanical seal, and are occasionally referred to as clamp rings. The drive is commonly achieved through the use of set screws which protrude from the drive ring to the shaft. The drive is passed from the drive ring to the other rotary components such as the seal faces through drive pins and sleeve components whilst the compression of o rings ensure that a fluid tight seal is maintained between the various components.
This method can be restrictive to the space that the seals that use it can fit in to due to the size of the set screws being a minimum diameter thereby requiring a minimum drive ring thickness. Alternative drive ring designs have therefore been devised, commonly in component seals, which use the drive ring as a constricting member which squeezes an elastomeric component onto the rotary shaft thereby providing drive between the rotating shaft into the drive ring. This rotation can then be passed by the elastomeric component or directly from the drive ring into other components and eventually into the rotary seal face. This method therefore provides a reduced size envelope however has the drawback that the drive ring may become detached from the correct location on the elastomeric component during installation.
One such example of a drive mechanism that ensures axial restriction is demonstrated in Roddis WO 2007/135402 and Roddis GB2391275 which overcomes this issue by having one of the pressed components diametrically larger than the other therefore allowing the two components to be axially located within one another. The drive between the two members is provided by numerous radially protruding male members which engage into a female portion in the second component. This design requires a large difference in diameter between the outer diameter of the drive ring and the shaft therefore potentially restricting its application.
Another such example is Keown WO2013076445 where the drive ring has the same diameter as the connecting component but axial restriction is still maintained through T-Profile sections. However, due to the profiles creating open portions a secondary section is required which does not have these sections removed to allow compression to be delivered around the entire circumference of the elastomeric component. This can therefore mean that the seal is too large for the cross sectional envelope and so restricting its use.